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Multiframe track-before-detect method based on velocity filtering in mixed coordinates

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Journal of Systems Engineering and Electronics 2022年第2期33卷 247-258页

作者： WANG liangliang ZHOU Gongjian School of Electronics and Information Engineering Harbin Institute of TechnologyHarbin 150001China Key Laboratory of Marine Environmental Monitoring and Information Processing Ministry of Industry and Information TechnologyHarbin 150001China

In this paper,a velocity filtering based track-before-detect algorithm in mixed coordinates is presented to address the problem of integration loss caused by inaccurate motion model in polar coordinate *** the motion of a con-stant velocity(CV)target is better modeled in Cartesian coordi-nates,the search of measurements for integration in polar sensor coordinates is carried out according to the CV model in Cartesian coordinates instead of an approximate model in polar sensor *** position of each cell is converted into Cartesian coordinates and predicted according to an assumed ***,the predicted Cartesian position is converted back to polar sensor coordinates for multiframe *** use of the correct model improves integration effectiveness and consequently improves algorithm *** handle the weak target with unknown velocity,a velocity filter bank in mixed coordinates is *** influence of velocity mis-match on the performance of filter bank is analyzed,and an effi-cient strategy for filter bank design is *** re-sults are presented to demonstrate the effectiveness of the pro-posed algorithm.

关键词： mixed coordinate approach velocity filtering multiframe integration weak target detection polar sensor coordinate

Effect of Operating Condition and Structural Parameter in the Hydrostatic Thrust CO_2 Bearing

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Journal of Thermal Science 2019年第3期28卷 454-462页

作者： LI liangliang XIE Yonghui Shaanxi Engineering Laboratory of Turbomachinery and Power Equipment School of Energy and Power EngineeringXi'an Jiaotong University

Hydrostatic thrust bearings are widely applied in rotating machinery field. Its comprehensive performance and safe operation is of great significance for ensuring equipment efficiency. In this paper, the numerical method is adopted to investigate the slit-restricted hydrostatic thrust CO_2 bearing with a small film thickness. The research is carried out from two aspects, which mainly consider the operating conditions and structural parameters. Firstly, the influence of different working fluid types including real air and CO_2(include subcritical and supercritical state) on the static characteristics of bearing is studied, and the results indicate that the bearing with CO_2 as working fluid has a better static performance. Secondly, the influence of rotor rotating speed is studied and the conclusion shows that the rotating speed has a significant effect on bearing static characteristics. Thirdly, the influence of different slit arrangement forms is investigated, and the consequence indicates that the circumferential slits show a better load capacity than that of radial slits, while the flow rate difference is small. Finally, the effect of film thickness on bearing static performance is investigated and the research shows that this factor affects static performance in a dramatical way. When the clearance tends to be smaller, the load capacity increases sharply, while the massflow rate of working fluid decreases.

关键词： slit-restricted supercritical carbon dioxide hydrostatic thrusting bearing slit arrangement film thickness rotating speed

Enrichment of Mississippi Valley-type(MVT) deposits in the Tethyan domain linked to organic matter-rich sediments

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Science China Earth Sciences 2023年第12期66卷 2853-2870页

作者： Yucai SONG Zhiming YANG liangliang ZHUANG SinoProbe Laboratory Institute of GeologyChinese Academy of Geological SciencesBeijing 100037China

The Tethyan domain hosts the world's most abundant hydrocarbon and Mississippi Valley-type(MVT) Pb-Zn resources. The relations among organic matter-rich sediments, MVT Pb-Zn mineralization, and the Tethyan tectonic evolution history are an important scientific issue. The data of paleogeographic reconstruction indicate that the Proto-, Paleo-, and NeoTethys oceans mainly lay in low latitude areas between 30°N and 45°S. The high temperature and precipitation and the lack of sea water overturning in stagnant basins resulted in high marine biological productivity and good preservation conditions for organic matter-rich sediments. Consequently, abundant organic matter-rich sediments were developed and preserved in the Tethyan domain and thus created abundant hydrocarbon resources. Mineralization age data demonstrate that MVT deposits mainly formed during the continent-continent convergence in the late stage of the Tethyan tectonic evolution. Deposits are located in the fold-and-thrust belts and forelands of the continent-continent convergence orogen, and spatially associated with hydrocarbon basins. Organic matter-rich sediments are well developed in MVT ore districts, where hydrocarbon activity appeared earlier than or nearly simultaneous with the Pb-Zn mineralization event. Hydrocarbon activity generally began earlier than the Pb-Zn mineralization in individual deposits. Organic matter-rich sediments and hydrocarbons mainly play the role of reducing agents in the MVT Pb-Zn mineralization process. Through bacterial or thermal reduction, dissolved sulfates from sedimentary strata were reduced to generate reduced sulfur for Pb-Zn sulfide mineralization. In summary, the Tethyan oceans have long been in low latitude areas near the equator, making the Tethyan domain develop abundant organic matterrich sediments and associated hydrocarbon resources which reduce sulfates to provide sufficient reduced sulfur for MVT PbZn mineralization in the region.

关键词： Tethyan domain Organic matter Mississippi Valley-type Pb-Zn deposit Low latitude Sulfate reduction

Stereoselective synthesis of substituted 1,3-dienes from propargylic esters: electrophilic-metal or redox catalysis?

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Science China Chemistry 2024年第5期67卷 1384-1396页

作者： Mengfu Dai liangliang Song Liang-An Chen Jiangsu Collaborative Innovation Center of Biomedical Functional Materials Jiangsu Key Laboratory of New Power BatteriesSchool of Chemistry and Materials ScienceNanjing Normal UniversityNanjing 210023China Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources International Innovation Center for Forest Chemicals and MaterialsCollege of Chemical EngineeringNanjing Forestry UniversityNanjing 210037China

1,3-Diene architectures are not only widely present in natural products, pharmaceuticals, and functional organic materials but also serve as versatile building blocks to furnish important functionalized molecules in synthetic chemistry due to conjugated repeating C=C units. Accordingly, various strategies to access substituted 1,3-dienes in a stereoselective manner have been developed. However, chemo-, regio-and stereoselective synthesis of highly substituted 1,3-dienes still remains elusive and challenging. Readily available propargylic esters have emerged as an appealing class of synthetic intermediates for accessing functionalized 1,3-dienes, especially challenging tri-or tetrasubstituted variants, via transition-metal catalysis, including electrophilic metal and redox neutral catalysis. This review, for the first time, systematically highlights recent advances in transitionmetal catalyzed synthesis of substituted 1,3-dienes from propargylic esters, discusses the mechanisms and synthetic utilities, and gives the remaining challenges and potential opportunities in this field.

关键词： 1 3-diene propargylic ester Lewis acid redox catalysis transition metal

A computational simulation study for techno-economic comparison of conventional and stripping gas methods for natural gas dehydration

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Chinese Journal of Chemical Engineering 2020年第9期28卷 2285-2293页

作者： Muhammad Salman liangliang Zhang Jianfeng Chen Research Centerof the Ministry of Education for High Gravity Engineering and Technology Beijing University of Chemical TechnologyBeijing 100029China StateKey Laboratory of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China

In the present work,the conventional natural gas dehydration method(CDM)and stripping gas method(SGM)are technically and economically analyzed,utilizing Aspen HYSYS and Aspen Process Economic Analyzer(APEA),*** optimize the CDM and SGM,the sensitivities of the water content of dry gas,reboiler duty and raw material loss are analyzed against solvent rate and stripping gas *** optimized processes are set to achieve a targeted value of water content in dry gas and analyzed at optimized *** analysis shows that SGM gives 46%lower TEG feed rate,42%lower reboiler duty and 99.97%pure regenerated ***,economic analysis reveals that SGM has 38%lower annual operating cost compared to *** to results,from both technical and economic point of view,SGM is more feasible for natural gas dehydration compared to CDM.

关键词： Natural gas dehydration Technical analysis Parametric optimization Economic study Aspen HYSYS

Conditional Regularity of Weak Solutions to the 3D Magnetic Bénard Fluid System

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Journal of Partial Differential Equations 2021年第2期34卷 144-169页

作者： MA liangliang Department of Applied Mathematics Chengdu University of TechnologyChengdu 610059China

This paper concerns about the regularity conditions of weak solutions to the magnetic Benard fluid system in R^(3).We show that a weak solution(u,b,θ)(·,t)of the 3D magnetic Benard fluid system defined in[0,T),which satisfies some regularity requirement as(u,b,θ),is regular in R^(3)x(0,T)and can be extended as a C∞solution beyond T.

关键词： Magnetic Benard fluid system regularity criteria conditional regularity Morrey-Campanato space Besov space

Full-Sized Pore Structure and Fractal Characteristics of Marine-Continental Transitional Shale: A Case Study in Qinshui Basin, North China

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Acta Geologica Sinica(English Edition) 2019年第3期93卷 675-691页

作者： YIN liangliang GUO Shaobin School of Energy resources China University of Geosciences(Beijing)Beijing 10083China Key laboratory of strategy evaluation for Shale gas Ministry of Land and ResourcesBeijing 10083China

Based on 10 shale samples collected from 4 wells in Qinshui Basin,we investigate the full-sized pore structure and fractal characteristics of Marine-Continental transitional shale by performing organic geochemistry,mineralogical composition,Nitrogen gas adsorption(N2 adsorption)and Nuclear Magnetic Resonance(NMR)measurements and fractal *** show that the TOC content of the shale samples is relatively high,with an average value of 2.44wt%,and the thermal evolution is during the mature-over mature *** NMR T2 spectrum can be used to characterize the fullsized pore structure characteristics of *** combining N2 adsorption pore structure parameters and NMR T2 spectrums,the surface relaxivity of samples are calculated to be between 1.7877 um/s and 5.2272 um/*** this basis,the T2 spectrums are converted to full-sized pore volume and surface area distribution *** statistics show that the pore volume is mainly provided by mesopore,followed by micropore,and the average percentages are 65.04%and 30.83%respectively;the surface area is mainly provided by micropore,followed by mesopore,and the average percentages are 60.8004%and 39.137%respectively;macropore contributes little to pore volume and surface *** pore structure characteristics of shale have no relationship with TOC,but strong relationships with clay minerals *** fractal dimensions Dmicro and Dmeso have strong positive relationships with the N2 adsorption fractal dimensions D1 and D2 respectively,indicating that Dmicro can be used to characterize the fractal characteristics of pore surface,and Dmeso can be used to characterize the fractal characteristics of pore *** shale surface relaxivity is controlled by multiple *** increasing of clay mineral content,pore surface area,pore surface fractal dimension and the decreasing of average pore size,will all lead to the decreasing of shale surface relaxivity.

关键词： Marine-Continental transitional shale nuclear magnetic resonance nitrogen adsorption full-sized pore structure fractal dimensions

Free vibration of FGM Timoshenko beams with through-width delamination

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Science China(Physics,Mechanics & Astronomy) 2014年第5期57卷 927-934页

作者： LI ShiRong FAN liangliang College of Civil Science and Engineering Yangzhou University School of Aerospace Xi'an Jiaotong University

Free vibration of functionally graded beams with a through-width delamination is investigated. It is assumed that the material property is varied in the thickness direction as power law functions and a single through-width delamination is located parallel to the beam axis. The beam is subdivided into three regions and four elements. Governing equations of the beam segments are derived based on the Timoshenko beam theory and the assumption of ＇constrained mode＇. By using the differential quadrature element method to solve the eigenvalue problem of ordinary differential equations governing the free vibration, numerical re- suits for the natural frequencies of the beam are obtained. Natural frequencies of delaminated FGM beam with clamped ends are presented. Effects of parameters of the material gradients, the size and location of delamination on the natural frequency are examined in detail.

关键词： functionally graded materials beam free vibration natural frequency differential quadrature method delamination

Multiframe weak target track-before-detect based on pseudo-spectrum in mixed coordinates

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Chinese Journal of Aeronautics 2022年第5期35卷 97-113页

作者： liangliang WANG Gongjian ZHOU Thiagalingam KIRUBARAJAN School of Electronics and Information Engineering Harbin Institute of TechnologyHarbin 150001China Key Laboratory of Marine Environmental Monitoring and Information Processing Ministry of Industry and Information TechnologyHarbin 150001China Department of Electrical and Computer Engineering McMaster UniversityONHamilton L8S 4K1Canada

Traditional multiframe Track-Before-Detect(TBD)may incur adverse integration loss resulting from model mismatch in sensor *** suboptimal integration strategy may cause target envelope *** address these issues,a pseudo-spectrum-based multiframe TBD in mixed coordinates is proposed *** data search for energy integration is conducted based on an accurate model in the x-y plane while target energy is integrated based on pseudo-spectrum in sensor *** algorithm performance is improved since the model mismatch is eliminated,and the pseudo-spectrum based integration facilitates well maintained target *** detailed multiframe integration procedure and theoretical target integrated envelope are ***,to cope with the unknown target velocity,a velocity filter bank based on pseudo-spectrum in mixed coordinates is *** effect of velocity mismatch on algorithm performance is analyzed and an efficient method for filter bank design is ***,a parameter estimation method using characteristics of integrated envelope is presented for improved target polar position and Cartesian velocity ***,numerical results are provided to demonstrate the effectiveness of the proposed method.

关键词： Mixed coordinates Multiframe detection Pseudo-spectrum Track-before-detect Weak target detection